Continuous casting mold



1366- 1958 F. w. VAUGHN ETAL CONTINUOUS CASTING MOLD Filed Dec. 10, 19562 Sheets-Sheet 1 INVENTORS 1 W m M m llllllllllllllllll||||||ll|||ll|l|l| 5 JEFRANK w. VAUGHN HARVEY B. DE VOE, JR. BY 4206.2%!

ATTORNEY Dec. 2, 1958 w VAUGHN ETAL 2,862,265

' CONTINUOUS CASTING MOLD 2 Sheets-Sheet 2 Filed Dec. 10, 1956""HIIHIIIHII' INVENTORJ FRANK w. VAUGHN HARVEY B. DE VOE JR.

ATTORNEY CONTINUDUS CASTING MOLD Frank W. Vaughn, Alexandria, Va., andHarvey B. De

Voe, Jr., Massena, N. Y., assignors to Aluminum Company of America,Pittsburgh, Pa., a corporation of Pennsylvania Application December 10,1956, Serial No. 627,379

Claims. (Cl. 22-571) This invention relates to the casting of ingots inbottomless molds by the continuous casting process and it moreparticularly relates to a device for directing cooling liquid over thesurface of the mold.

In the continuous casting process the molten metal is fed into the topof an open end mold and solidified metal is withdrawn from the bottom ofthe mold. To secure a rapid solidification of the metal, the mold mustbe drastically chilled and this is generally accomplished by floodingthe external surface of the mold with a liquid coolant such as water. Tofacilitate the rapid transfer of heat from the freezing metal to thecoolant, the mold is usually made with a thin wall and a good'heatconductive material is employed such as copper or aluminum or alloysthereof. Because the mold has thin walls, it is convenient to refer toit as being a mold shell. The mold shell and descending ingot may bechilled by projecting a copious amount of water against the shell overthat portion of the external surface which corresponds to the inside ofthe mold in contact with or in close proximity to molten metal and theforming ingot. Where this means of cooling is employed, it is a commonpractice to allow the water to run down from the mold onto the surfaceof the ingot emerging therefrom. In place of such an open coolingsystem, the mold shell may be surrounded by a chamber through which thecoolant is circulated. One modification of the cooling chamberarrangement has been proposed which consists of providing openings inthe bottom of the chamber whereby a portion of the circulated coolantdrops upon the ingot as it descends from the mold. In the foregoing moldcooling practices a relatively large volume of coolant is employed at arelatively low pressure.

In operation it has been found that where perforated pipes or nozzlesare used, the openings occasionally become plugged wit-h a resultantnon-uniform cooling of the mold and, therefore, with adverse effect uponthe ingot formed therein. In the case of jacketed molds, the transfer ofheat from mold shell to the liquid coolant is sometimes impeded becauseof the accmulation of gas or vapor bubbles on the surface of the moldand the failure of the stream of water passing through the coolingjacket to sweep away the bubbles. An increase in the pressure and volumeof the coolant supplied to the jackets does not necessarily overcomethat condition or produce a corresponding increase in the chillingeffect because of increased difficulty in obtaining a uniformdistribution of the incoming coolant over the mold surface. Moreover,the use of a larger volume of coolant requires that additional meansmust be provided for handling the coolant discharged from the coolingchamber.

Our invention is directed to increasing the chilling efiiciency of thecoolant and creating conditions favorable to a higher rate of withdrawalof the ingot from the mold. One of the objects of our invention is topronited States atent ice casting mold which directs the coolant overthe mold surface. Another object is to provide means within the coolingchamber surrounding a continuous casting mold to increase the flow ofcoolant over the mold surface without loss in uniformity of coolingeffect. Still another object is to provide a device in the coolingchamber surrounding a continuous casting mold which is selfadjustingwithin limits and yet maintains a minimum width of passageway for thecoolant to pass over the mold surface.

We have discovered that the foregoing objects and others can be achievedby providing a sleeve within the cooling chamber surrounding the moldshell which is spaced but a short distance from the shell and whichextends over at least that portion of the mold shell wherein the moltenmetal and the freezing ingot are located. Space is left at the top andbottom of the sleeve within the chamber for the coolant to enter andleave the narrow passageway between the sleeve and mold shell but all ofthe coolant entering the chamber must go through the passageway beforeit is discharged from the chamber. By means of this arrangement it hasbeen found that a relatively high velocity sheath of coolant is producedwhich passes over the mold surface. The high velocity is obtainedwithout increasing. the pressure of the coolant supplied to the chamber.As a matter of fact, a relatively low pressure supply can beconveniently employed and still secure the necessary rapid flow ofcoolant over the surface of the mold shell. The rapidly moving streamof. coolant effectively chills the mold and prevents the accumulation ofany gas or vapor bubbles on the surface of the mold. Also, by reason ofthe more effective chilling of the mold, it is ,sometimes possible toincrease the rate at which the ingot is withdrawn from the mold. Weh'avefound that the rapidly moving stream of coolant provides a uniformchilling around the entire periphery of the mold and I that the sleeveprevents any direct impingement of'the coolant upon the mold surface asit enters the cooling chamber. The sleeve is not rigidly attached toeither the mold or the surrounding chamber but is held in place byhydraulic pressure within the chamber and separate elongated spacerelements between the sleeve and the mold. which maintain a passageway ofpredetermined minimum width. The self adjustment of the sleeve withinthe cooling chamber eliminates a tedious and painstaking positioningwhich would be necessary if the sleeve were rigidly supported and italso permits a certain degree of response to any change in shapeoralignment of the mold such as occasioned by warpage of the mold.

The above features and others will become clearer through reference tothe accompanying figures wherein Fig. 1 is a top plan view of acontinuous casting unit including a metal transfer trough;

Fig. 2 is a side elevation, partially in section, taken on line 22 ofFig. 1;

Fig. 3. is a side elevation of a modification of the apparatus shown inFig. 2; p

Fig. 4 is a top view of the sleeve element seen in Fig 2, and

Fig. 5 is a vertical section of Fig. 4 taken on line 5-5.

Referring to Fig. l, the mold shell 10 is supported on table 14 by theflange 12 attached to the mold. The table in turn is connected to themain frame 16. Molten metal 34 is delivered from a source, not shown, tothe transfer trough 18 from which it descends into the mold and formspool 36. Control of the metal flow is effected by a manually operatedvalve supported by threaded block 24 which in turn is mounted on bracket26, the handle of the valve appearing at 20. The vertical wall of thewaterchamber below the table is'shown in dotted lines at 48 togetherwith pipes 54 which supply water to the C.hamber. Sleeve 58, described,below, surrounds the .mo'ld'lt) and is spaced therefrom by wires 62.

. More details of the ,apparatus are apparent in'the sec- ,tionalview inFig. 2. 'The transfer trough 18, carrying molten metal 34, is providedwith a downspout flange 28 and amp'ple30 secured thereto having a bottomdischarge port'32. Themetal flow control valve consists of stem ..22having a threaded portion which engages comple- .mentary threads'insupporting block 24 mounted on bracket 26. By turning the valve stem thelower end is adjusted with respect to the discharge port thuscontrollingthe volume of metal entering the mold. A pool of molten metal36 is maintained at asusbtantially constant level once the pouringoperation has commenced. Themetal freezes inwardly from the mold wallforming a 2crater-like cavity and eventually the completely solidifiedingot38. The ingot rests upon mold bottom 40 carried on platform 42thatis raised and lowered by the hydraulic r'ram arm 44. The ram is situatedin apit, not shown,

into which the ingot descends and from which it is hoisted uponcompletion of the casting operation.

The water chamber 46, which completely surrounds the mold shell andextends over substantially the entire height of the mold, has an outervertical wall 48, conveniently made of a channel member, and a bottompor- ,tion' 50.v Bolted to the bottom 50 is a deflector plate 52 havinga bevelled edge for directing the water dropping from the water chamberagainst the ingot descending from the mold. To prevent escape of waterfrom the top of the chamber, a gasket 13 is provided between flange 12and table 14. Water is supplied to the chamber through pipes 54 andopenings 56 in the channel member 48.

Withinthe chamber and close to the mold shell -is sleeve 58 whichextends around the entire periphery of the mold shell and is oppositethat portion of the shell which holds the liquid and the solid metal. Inthis manner this portion of the mold shell is effectively chilledthrough the functioning of the sleeve as described below. The sleeve issupported upon an inner chamber wall member 70, which is shorter thanthe outer wall member 48, through welded sleeve flange 60 intermediatethe top and bottom of the sleeve with gasket 72 positioned between theflange and the upper edge of member 70 to substantially eliminateleakage of any water from the water chamber. The inner wall member'70,which may be in the form of a narrow plate section, is welded to thebase of the water chamber thus forming a chamber having integral sidewalls and base. In addition to serving as a support for the sleeve, themember 70 also acts as a baffle to the incoming stream of water from thepipes. In mounting the member 70 on chamber base 50, suflicient spaceshould be. left between it and the sleeve to accommodate. the bent endsof the spacer elements and not inter- ..fere with the'lateral movementor adjustment of the determinedspacing between the mold and sleeve. The

vertically positioned spacer wires 62 are initially bent into the. shapeof a flat U, the ends passed through holes near the top and bottom ofthe sleeve and then bent at right angles to hold the spacer element inplace. If desired the spacer elements may consist of a single wire asshown in Fig. 5, running from one vertical element to "theothen. It willbe appreciated that other shapes of .,spacer .elements may be employedproviding they'are relatively thin and in contact with such a smallarea'of the mold as not to interfere with chilling of the mold shell. Itis obvious that the axis of the spacing elements should be parallel tothelstream of coolant and offer a minimum obstruction to the flow of theliquid. The shape of the sleeve in Fig. 2 and the location of the wireholes are seen more clearly in Figs. 4 and 5. The sleeve 58 is spacedfrom the mold over at least a major portion of its height by a; distanceapproximately equal to the diameter of the wire thereby providing a thinsubstantially uniform pasageway around the entire mold shell. Althoughthe spacing elements may be continuous bodies as illustrated they mayalso be in sections, one directly above the other, or in a staggeredarrangement. The length of the spacing elements and their arrangement isa matter of choice depending upon the size of the sleeve.

Under some conditions it is desirable to reduce the rate of flow ofcoolant through the passageway between the sleeve and mold shell. Thiscan be accomplished by providing a relatively narrow band at the base ofthe sleeve as indicated at 68. The band may be of any thickness as longas the passageway between the sleeve and the mold is of suflicientwidthto permit a continuous flow of liquid and the rate of flow above theconstr cted region is not reduced to such a level as to impair chillingof the mold shell. A reduction in width of the passageway by as much as50% can be effected without loss 1n cooling efficiency above theconstriction.

The sleeve 58 should be terminated short of the bottom of the coolingchamber and the bottom edge of the mold shell thereby allowing thecoolant to pass under the lower edge of the sleeve. In the arrangementin Fig. 2 the space 67 between the lower edge of the sleeve and thedeflector plate 52 also serves to permit escape of any water which mayaccumulate between the sleeve and inner chamber wall 70. It is important1n any case that the sleeve extend almost to the bottom edge of the moldshell to insure cooling of the shell with the rapidly flowing sheath ofcoolant.

The sleeve is maintained in sealing relationship to the gasket 72 andinner wall member 70 by the exertion of hydraulic pressure against thesleeve and the supporting flange 60. Moreover, the hydraulic pressurepermits a degree of self-adjustment of the sleeve that would not occurin a rigid connection between the flange 60 and wall 70.

In the modification of the apparatus shown in Fig. 3, the water is notdischarged from the cooling chamber onto the ingot, instead it leavesthe chamber through a pipe. In this arrangement of mold and coolingchamber, the mold is supported by flange 12 which is bolted to topflange 82 rigidly attached to the outer vertical chamber wall member 80.A gasket 13 between the two flangesprevents any leakage of water. Thetop flange 82 is also bolted to the moldtable l4 and the latter issupported on a main frame 16. The cooling chamber is divided into twoparts, an upper portion 74 and a lower portion 76, the two beingseparated by a horizontal wall 78 and the supporting flange 60 attachedto the sleeve 58. The bottomof the lower portion is formed fromintegrally attached flange 86 and bottom plate 88 bolted thereto withgasket 90 between the two members which extends beyond them to engagethe lower edge of the mold shell and thus establish a water tight seal.A rigid connection can be madc between the bottom of the chamber and thelower edge of the mold but this makes assembly and disassembly of themold unit more difiicult and is therefore less satisfactory from thestandpoint of maintenance. The water is supplied to the upper portionthrough pipe 92 and it is discharged from the lower portion of thechamber through pipe 94. A gasket 72 is provided between flange 60 anddividing wall 78 to seal the upper portion of the chamber from the lowerportion and thus force all of the water entering the upper portion 74 topassthrough the narrow passageway between the sleeve and the mold beforethe mold with wires as described above and a raised rim portion 68 maybe provided at the bottom of the sleeve.

, Other kinds of spacing elements may be employed and they may be insections arranged as desired as has been mentioned above.

It is a characteristic of our cooling system that all of the coolant,except for leakage losses, enters a chamber and is compelled to passthrough the narrow space between the sleeve and mold shell before beingdischarged. Moreover, the coolant need not be under a high pressure, ithaving been found that a pressure Within the chamber of less than 1 lb.per sq. in. is sufiicient to provide the desired flow. The pressure inany case must be positive, that is, above atmospheric pressure.

It will be appreciated that although the mold described above is square,the invention is applicable to rectangular, polygonal and circularmolds. Also, the length of the mold may vary but generally those of theshort type such as employed in the direct chilling process arepreferred.

As an example of a suitable mold and cooling chamber of the type shownin Figs. 1 and 2 the mold may consist of a A" thick plate of aluminumalloy and may be approximately 12" square and have a height ofapproximately 7 /2". The sleeve element may likewise consist of a A"thick aluminum alloy plate and have an aluminum alloy flange Weldedthereto intermediate the top and bottom of the sleeve. The spacer wiresemployed may be approximately 4; in diameter so that the passagewaybetween the sleeve and the mold shell over the major portion of thesleeve height will be approximately A3" in width. The wires should bemade of aluminum, preferably, to minimize corrosion. The

. raised band 68 may be approximately in thickness and 1" in height thusreducing the width of the passageway to about $5 The cooling chamberadapted to serve the foregoing mold may be about 6" in height and about2" in width. In the case of the mold and chamber seen in Fig. 3, themold and chamber may be about 10" in height and the chamberapproximately 3" in width.

To effect the desired cooling of the mold the .water can be supplied ata rate of about 80 gallons per minute under a relatively low pressure ofless than one lb. per sq. in. Within the /s wide passageway between thesleeve and mold shell it will have a velocity of approximately 240 feetper minute at this pressure. However, at the reduced section of thepassageway at the bottom of the sleeve the velocity will be increased toabout 480 feet per minute. It is, therefore, evident that a highvelocity stream of water effectively wipes the mold surface and removesany steam bubbles which might tend to develop. Under these conditions ithas been possible to increase the rate of lowering the ingot by as muchas 1" per minute over the normal lowering rate. v

To cast a light metal ingot in the apparatus described above, the moldbottom 40 is moved up into the mold shell, the water chamber filled andcirculation of water commenced. Molten metal is gradually fed to themold and a pool of metal created which is maintained at substantially aconstant level after the casting operation has started. The molten metalfreezes from both the bottom and the sides of the mold cavity. When asufii'cient amount of metal has frozen the mold bottom is lowered withthe embryo ingot resting thereon. The pouring and chilling operationsare continued until the desired length of ingot has been obtainedwhereuponthey are stopped and the ingot removed. To secure a sounduniform ingot, the chilling of the mold walls must be uniform. Theclosely spaced sleeve described above accomplishes this result.

Although the apparatus has been described in conneca metal layer is tobe cast upon a central core. Thus, a core in the form of an ingot orwrought article, of suitably smaller transverse dimensions than the moldmay be passed through the mold and molten metal cast against it whichwhen frozen provides the desired layer or cladding. The molten layermust be chilled in the same manner as an ingot to produce a sounduniform cast layer.

It will be appreciated that the size and shape of the ingot may vary,the larger ingots being lowered from the mold at a lower rate thaningots of relatively small cross section because of the greater amountof heat which must be extracted from the larger mass of molten used informing the large ingots.

The apparatus for casting the molds can be used in casting many metalsbut it has proved to be most successful. in casting the light metals,aluminum, magnesium and the alloys wherein these elements constitute themajor portion of the alloy composition.

Having thus described our invention and certain embodiments thereof, weclaim:

1. In a continuous casting mold unit, an open ended mold and means forcooling said mold, said means comprising a liquid coolant-containingchamber completely surrounding said mold and extending oversubstantially the entire length thereof, said chamber having inner andouter walls, the mold itself constituting at least a portion of theinner wall, means for supplying liquid coolant to said chamber and selfadjusting means within said chamher for directing the coolant over thesurface of the mold at a relatively high velocity, saidcoolant-directing means comprising a movable sleeve around the entiremold and parallel thereto, said sleeve being opposite at least thatportion of the mold which contains the molten and solidified metal andof a length less than that of the cooling chamber, said sleeve alsobeing supported intermediate the top and bottom thereof with freedom forlimited lateral movement and spaced from the top and bottom of thechamber, and flexible separate spacing elements mounted at intervalsaround said sleeve on the side facing the mold, which elements when incontact with the mold define the minimum width of a narrow passagewaybetween said sleeve and mold over at least the major length of thesleeve, said spacing elements consisting of thin elongated membersdetachable from the sleeve and *iounted on said sleeve in a directionsuch that their axes are parallel to the direction of the flow ofcoolant through the passageway between the sleeve and mold, the upperend of said passageway being in communication with the upper portion ofthe coolant chamber whereby all of the coolant entering the chamberenters the passageway and is discharged therefrom after passage over themold surface.

2. In a continuous casting mold unit, an open ended mold and means forcooling said mold, said means comprising a liquid coolant-containingchamber completely surrounding said mold and extending oversubstantially the entire length thereof, said chamber having inner andouter walls, the mold itself constituting at least a portion of theinner wall, means for supplying liquid coolant to said chamber and selfadjusting means within said chamber for directing the coolant over thesurface of the mold at a relatively high velocity, said coolantdirecting means comprising a movable sleeve around the entire mold andparallel thereto, said sleeve being opposite at least that portion ofthe mold which contains molten and solidified metal and of a length lessthan that of the cooling chamber, a peripheral flange integrally joinedto said sleeve on the side facing the outer chamber wall, said flangebeing located intermediate the top and bottom of said sleeve, saidflange resting upon and in compressive sealing relationship to a portionof the chamber wall extending into the chamber and toward said flange,said flange and sleeve being laterally movable with respect to thechamber wall extension, said flange in cooperation with said chamberwallextension providing a complete substantially liquidtight barriertoescape of coolantfrom the chamber, said elements when in contact withthe mold define the minia mum width of a narrow passageway between thesleeve and the mold, said spacing elements consisting of thin elongatedmembers detachable from the sleeve and mounted thereon in a directionsuch that their axes are parallel to thev direction of the flow ofcoolant through the passageway between the sleeve and mold.

3. In a continuous casting mold unit, an open ended mold and means forcooling said mold, said means comprising a liquid coolant-containingchamber completely surrounding said mold and extending oversubstantially the entirelength thereof, said chamber having inner andouter walls, the mold itself constituting at least a portion of theinner wall, means for supplying liquid coolant to said chamber and selfadjusting means within said chamber for directing the coolant over thesurface of the mold at a relatively high velocity, saidcoolant-directing means comprising a movable sleeve around the entiremold and parallel thereto, said sleeve being opposite at least thatportion of the mold which contains the molten and solidified metal andof a length less than that of the cooling chamber, said sleeve alsobeing supported intermediate the top and bottom thereof with freedom forlimited lateral movement and spaced from the top and bottom of thechamber, and flexible separate spacing elements mounted at intervalsaround said sleeve on the side facing the mold, which elements when incontact with the mold define the minimum width of a narrow passagewaybetween said CJi through the passageway betweenthe sleeve and mold, saidsleeve being supported by a peripheralflflange integrally joined theretoon the side facing the outerchamber wall intermediate the top and,bottom 'of the sleeve, said flange resting upon and in sealingrelationship to the short vertical chamber wall intermediate the moldand outer chamber wall, with a yieldable sealing element between saidflange and the top edge of the short vertical sleeve and mold over atleast the major length of the sleeve, said spacing elements consistingof thin elongated members detachable from the sleeve and mounted on saidsleeve in a direction such that their axes are parallel to the directionof the flow of coolant through the passageway between the mold andsleeve, the portion of the sleeve below the spacing members beingthicker and consisting of a band of uniform width and thickness on theside of the sleeve'facing the mold, said band serving to reduce thewidth of the passageway and increasing the velocity of the coolantpassing the band as compared to the velocity above the constrictedregion, the upper end of said passageway being in communication with theupper portion of the coolant chamber whereby all of the coolant enteringthe chamber enters the passageway and is discharged therefrom afterpassage over the mold surface.

4. In a continuous casting mold unit, an open ended mold and means forcooling said mold, said means comprising a liquid coolant-containingchamber completely surrounding said mold and extending oversubstantially the entire length thereof, said chamber having inner andouter walls, the mold itself constituting the inner wall, a verticalwall portion shorter than the outer wall intermediate the mold and outerwall, but parallel to said outer wall, means for supplying liquidcoolant to said chamber and self adjusting means within said chamber fordirecting the coolant over the surface of the mold at a relatively highvelocity, said coolant-directing means comprising a movable sleevearound the entire mold and parallel thereto, said sleeve being oppositeat least that portion of the mold which contains liquid and solidifiedmetal and of a length less than that of the cooling chamber, said sleevehaving spacing elements mounted on the side facing the mold, saidelements being mounted atintervals on the sleeve and when in contactwith the mold define the minimum width of a narrow passageway betweensaid sleeve and mold, said spacing elements consisting of thin elongatedmembers detachable from the sleeve and mounted thereon in a directionsuch that their axes are parallel to the direction of the flow ofcoolant wall, said flange and said short wall serving as a barrier tothe escape of coolant from the'chamber, the portion the sleeve below theperipheral flange being in contact with the coolant traversing thepassageway and spaced from thesaid short vertical chamber wall, thepassageway between the sleeve and mold terminating at the lower edge ofthe sleeve and the coolant being discharged therefrom and directedagainst the solidified metal body descending from the mold.

5. In a continuous casting mold unit, an open ended mold and means forcooling said mold, said means comprising a liquid coolant-containingchamber completely surrounding said mold and extending oversubstantially the entire length thereof, said chamber having inner andouter walls, the mold itself constituting the inner wall, said chamberbeing divided into upper and lower portions by a horizontal wall incooperation with a flange supporting coolant directing means, means forsupplying coolant to the upper portion of the chamber and means forreceiving coolant discharged from the lower chamber portion, selfadjusting means within both of said chambers for directing the coolantover the surface of the mold at a relatively high velocity, saidcoolantdirecting means comprising a movable sleeve around the entiremold and parallel thereto, said sleeve being opposite at least thatportion of the mold which contains liquid and solidified metal and of alength less than that of the cooling chamber, said sleeve havingflexible separate spacing elements mounted thereon at intervals on theside facing the mold which when in contact with the mold define theminimum width of a narrow passageway between the sleeve and mold, saidspacing elements consisting of thin elongated members detachable fromthe sleeve and mounted thereon in a direction such that their axes areparallel to the direction of the flow of coolant through the passagewaybetween the sleeve and mold, said sleeve having a peripheral flangeintegrally joined thereto on the side facing the outer chamber wall andintermediate the top and bottom of the sleeve, said flange resting uponand in sealing relationsip to the horizontal wall dividing the coolingchamber into upper and lower portions, a yieldable sealing element beingprovided between said flange and said horizontal wall, the flange andhorizontal wall together serving as a barrier to escape of coolant fromthe upper to the lower portions of the cooling chamber except throughthe passageway between the sleeve and mold, the passageway at both topand bottom being in communication, respectively, with the upper andlower portions of the cooling chamber whereby all of the coolantentering the upper portion of the chamber enters the passageway and thecoolant discharged from the passageway is discharged into the lowerportion of the cooling chamber.

References Cited in the file of this patent UNITED STATES PATENTS1,503,479 Coats Aug. 5, 1924 2,187,720 Williams Jan. 23, 1940 2,590,311Harter et al. Mar. 25, 1952 2,613,411 Rossi Oct. 14, 1952 FOREIGNPATENTS 835,790 Germany Apr. 3, 1952 932,085 Germany Aug. 22, 1955

